Have you ever thought about what is actually going on in your body when you throw back that energy drink or sip that coffee?
How is caffeine broken down and how does it affect your metabolism? How long does caffeine stay active in your system and why do people crave the stuff?
We’ll try to answer those questions and more in the simplest terms possible, so that you can be an educated consumer when it comes to caffeine metabolism.
Caffeine From the First Sip
Caffeine easy passes through body membranes so from the first sip the caffeine is entering your blood stream through the lining of your mouth, throat, and stomach. It only takes 45 minutes for 99% of the caffeine to be absorbed through these membranes.
In humans the half-life for caffeine is anywhere from 2.5 to 4.5 hours, which explains why the average energy drink or coffee’s effect lasts about 2 to 3 hours. Things like age, medical conditions, and drug interaction can have an effect on the half-life.
Caffeine in the Blood Stream
While most research on caffeine has been conducted using animals, the data has been converted to show the most likely effect on the human body. As soon as the caffeine enters the body it is already being metabolized by the liver and broken down into theophylline, theobromine and paraxanthine.
From there these chemicals travel throughout the body where they affect various body functions. The most studied of these is the way caffeine is similar to the molecule adenosine in the brain. The caffeine molecules bind to the adenosine receptors in brain cells and block adenosine from binding.
This causes elevated levels of adenosine in the blood which is believed to cause feelings of alertness and energy. The compounds also interact with the dopamine system in the brain which influences mood and prevents dopamine’s calming effect.
There also has been research into the way adenosine may play a role in the sleep-wake cycle. Caffeine doesn’t replace the person’s need for sleep, but just covers up drowsiness symptoms.
Theophylline relaxes smooth muscles, which has been beneficial to those with asthma and is the reason why after drinking caffeine a person often feels the need to use the bathroom as it is affecting the smooth muscle of the colon. Theobromine increases the amount of oxygen and nutrients that can be used by the brain and muscles.
There have been many other researched effects of caffeine covered by Energy Fiend, but the above represents the most researched and common.
Caffeine’s Exit from the Body
The caffeine metabolites are then filtered by the kidneys and they exit the body with the urine. Caffeine has been shown to have a diuretic effect on the body, which basically causes the body to release more water in the urine. However, new research suggests that this is only in people who have not built up tolerance to the caffeine molecule.
When caffeine has exited the body or has been used by the various cells of the body the person can experience a “crash” that is caused by elevated levels of adenosine and dopamine finally being able to attach to brain cell receptors. This causes feelings of tiredness and fatigue. Prolonged use of caffeine also causes withdrawal symptoms.